Orthopedic device

ABSTRACT

An orthopedic device comprising a plastic sheet member having one side covered with a thin protective layer which is substantially thinner than said plastic sheet member and the other side covered with an insulating layer, e.g., fabric or foam. The plastic sheet member has a tensile strength of at least 2,000 psi. The orthopedic device is formable at temperatures above about 120° F.

BACKGROUND OF THE INVENTION

This invention relates to orthopedic devices having broad medicalapplications. These devices are used to support, position, protect,immobilize and/or restrain portions of the body.

Orthopedic devices is a broad term that is used to describe medicalstructures such as casts, splints, supports, braces and other meansutilized to support, immobilize, restrain, protect and position bodyportions. They are used in many fields, including the physical medicineand rehabilitation field, general medicine, neurological field, and theveterinary field. They are also used to prevent recurrance of previousdisabilities, and to prevent discomfiture and subsequent disability.

Different types of the known orthopedic devices have specific uses andit has been necessary to select a specific type of orthopedic device tomeet the requirements of a specific intended usage. The treatment offractures usually requires total immobilization. Casts made of Plasterof Paris (plaster) are commonly used for this purpose. Plaster castshave the disadvantage that it takes hours to harden, the cast isexcessively heavy, it has poor compression strength and is readilycrushed or broken, and it has poor resistance to water and poor x-raypenetrability. Splints have been made of wood and metal and evenplastic. Those synthetic base orthopedic devices which have beenproposed and/or introduced commercially by others have had disadvantagesinherent in some or all uses.

Orthopedic devices should desirably be lightweight. They should becapable of immobilizing a portion of the body when that is the intendedpurpose. Similarly, they should be capable of resiliant support and/orcushioning when that is required. The orthopedic device should becapable of being formed in a practical manner and without discomfort tothe patient. Additionally, the orthopedic device should not haveproperties which irritate the patient during the period in which it isin service. Orthopedic devices fulfilling these requirements aredisclosed in my copending application, Ser. No. 465,404, filed Apr. 29,1974.

It is an object of this invention to provide orthopedic devices havingwide applicability and a unique combination of desirable properties.

SUBJECT MATTER OF THE INVENTION

The orthopedic device of the present invention is a plastic sheet memberhaving at least one side covered with a thermally insulating layer. Theplastic sheet member is at least about 40 mils thick. The insulatinglayer is at least about 10 mils thick. It is capable of being molded(formed) with application of normal finger pressure when the plastic isat a temperature above about 120° F. When the device is heated tosubstantially above its molding temperature, e.g., 165°-350° F, andallowed to cool in air and ultimately on the patient as it is beingformed, the temperature at the outside of the insulating layer is atleast about 25° F cooler than the plastic member and preferably at least40° F cooler.

The orthopedic device has both sides of the plastic sheet membercovered. The side covered with the insulating layer is the insidesurface of the device and is the side intended to be placed against thebody surface during service. The other side (the outside of the device)is covered with a fabric layer (referred to herein as the "outside" or"other" of "protective" which is preferably fabric and protects theplastic. The insulating layer is bonded to the plastic and the outsidefabric layer is bonded to the plastic sheet member. The outside fabriclayer is preferably between about 4 and 22 mils thick.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rectangular blank having a construction in accordance withthe present invention.

FIG. 2a is an enlarged cross section along the line 2--2 of FIG. 1 ofone embodiment of the invention.

FIG. 2b is an enlarged cross section along the line 2--2 of FIG. 1 ofanother embodiment of the invention.

FIG. 3 is a perspective of a formed back support having a constructionin accordance with the embodiment of FIG. 2a; and

FIG. 4 is a perspective of a formed arm splint having a construction inaccordance with the embodiment of FIG. 2a.

When the insulating layer is a fabric, it may be a woven, felted,matted, batted or knitted fabric. When it is a woven fabric, it ispreferably between about 10 mils and 22 mils thick. Some fabrics, e.g.,felt, may be considerably thicker and provide cushioning. The preferredinsulating fabric is a woven blend, preferably 50:50, of ahigh-temperature aromatic polyamide, now generically classified as anaramid, and a high-temperature cross-linked phenol-formaldehyde fiber,such as the no-burn fabrics marketed by Collins & Aikman Corp. which areblends of 50% Kynol and 50% Nomex. Nomex is a trademarked product of theDu Pont Company and is the high-temperature aromatic polyamide. Kynol isa trademarked product of the Carborundum Company and is a cross-linkedphenol-formaldehyde fiber, such as that described in U.S. Pat. Ser. No.3,650,102. An aramid fabric may also be used.

The insulated fabrics may be used in weights of about 4 oz. per squareyard, up to about 16 oz. per square yard. The preferred weight is about5 to 8 oz. per square yard.

The insulating layer preferably should have a coefficient of heattransfer below about 2 cal/sec/cm² /cm/°C×10.sup.⁻⁴, and more preferablybelow about 1.6 cal/sec/cm² /cm/°C×10.sup.⁻⁴.

When the insulating layer is a fabric layer, it is preferably affixed tothe central plastic member with an adhesive, preferably a thermoplasticadhesive. Since relatively high shaping and molding temperatures, e.g,400° F, may be used to shape the orthopedic device, the thermoplasticadhesive should be one which will remain bonded to the fabric and to thecentral plastic member at the temperatures used to heat and form thedevice. It is preferred that it should retain said property attemperatures above 200° F and for an added safety factor, it ispreferred that it should retain said property at above about 350° F fordevices which will be shaped before services.

The outside adhesive may be a polyurethane;

preferably a flexible thermoplastic polyester type polyurethaneadhesive. This material also has the advantages of good resistance toperspiration, washing and dry cleaning. Although the polyester typepolyurethanes are preferred, polyether types may also be used.Thermosetting polyurethane adhesives may also be used, such as hydroxylterminated hexanediol adipate polyester cross-linked with about 4% of4,4'-diphenyl methane diisocyanate, which is preferably halogenated toimprove its flame retardancy.

An extruded polyester sheet about 21/2-3 mils thick is also a preferredadhesive. It is positioned between the central plastic sheet and thefabric layer and the materials heated to about 350° F at a pressure of1-2 psi to affix the fabric to the central plastic member.

Alternate but less preferred adhesives include the acrylates, such aspolyethyl acrylate, polybutyl acrylate, and polyethylhexyl acrylate; anda polyvinyl acetate homopolymer and a copolymer of ethylene and vinylacetate. The adhesive may also be blends of the foregoing.

The adhesive may be coated as a thin layer on the central plastic memberand the fabric layer positioned on the adhesive, usually with theapplication of pressure. This will usually result in the adhesivepenetrating into the fabric layer. With a combination of a sufficientlythin adhesive layer and sufficient pressure during application, theremay be some direct contact of some of the fabric with the centralplastic member

The fabric, particularly when woven, may be partially or whollyimpregnated with a plastic adhesive before being applied to the centralplastic layer. The preferred insulating fabric layers are partiallyimpregnated, with the impregnating plastic being applied from onesurface to a depth of between about 0.1 mil and 7 mils and preferablybetween about 0.05 and 5 mils. This results in a thin coating on thesurface of the fabric, which is applied hot (or heated afterapplication) and affixes the impregnated fabric to the central plasticmember.

The fabric layer may also be bonded to the plastic member by fusing,i.e., heating until the plastic is viscous, at a temperature above about325° F, and then contacting the fabric with pressure so that the surfaceof the plastic partially impregnates the fabric and upon cooling isbonded thereto.

The insulating layer may also be a plastic foam layer. The foam layerprovides sufficient insulation so that the outer surface of the foamlayer may contact the person without severe discomfort while the plasticsheet member is still soft and usually at a temperature substantially inexcess of about 120°-130° F. The insulating foam layer may also functionto cushion the portion of the person against which the orthopedic deviceis applied.

Since foam layers may be produced having substantially differinginsulating characteristics and since the amount of padding desiredvaries in different applications, the thickness of the foam layer mayvary from as little as about 10 mils up to about 300 mils. For mostservice applications in which some cushioning is desired and/or is notdetrimental, foam layers having a thickness of between about 125-250mils are preferred. Even thicker layers, e.g., up to about 500 mils, maybe useful to pad a portion of an orthopedic device which will contact aboney portion of the person, particularly when pressure may be appliedby this boney portion against the orthopedic device. In someapplications in which very precise positioning of the body portionwithout the possibility of movement is desired, relatively thin foamlayers e.g., between about 25 and 75 mils thick are useful. In someapplications, a thin foam layer may be used largely because there is nofurther advantage to a thicker layer and the thin layer would be moreeconomic.

It is preferred that the foam layer should be relatively stiff so thatit does not readily compress under pressure. This has the dualadvantages that the insulating characteristic of the foam is retainedwhen the foam layer is under pressure. This is particularly importantsince the orthopedic device is usually "pressed" against the body whenit is formed. A relatively stiff foam layer is also an advantage in thatit provides more accurate positioning and minimizes the amount ofpermissible movement of the body portion against which the orthopedicdevice is applied. The foam layer comprises a cellular structure havinga great many pores in the plastic material. The foam may be of a closedpore construction or of an interconnected (open) pore construction, or acombination of both as is the usual instance. The relative stiffness ofthe foam is preferably controlled by the selection of polymerconstituents which produce a relatively stiff foam.

When the orthopedic device is heated sufficiently so that it will remainsoft for several minutes during which it is shaped and formed, theplastic sheet member is usually heated to a temperature well above 200°F and is often heated to temperatures of at least 300° F and sometimesup to as much as about 350°-375° F. The insulating foam layer mustremain stable at the temperature to which the orthopedic device isheated. If the foam layer is not stable at these temperatures, thecellular structure would collapse as a consequence of viscous flow,particularly when pressure is applied. Since destruction of the cellularstructure would impair the insulating characteristics of the foam andalso the cushioning characteristics of the foam, those foams which arestable at above 200° F are preferred and those foams which are stable attemperatures as high as at least 300° F are particularly preferred.

It is preferred that the foam layer should not support combustion, i.e.,not burn, or that it should have at least as good flame-retardantcharacteristics as the plastic sheet member which is preferably apolyvinyl chloride composition. It is preferred that the foam layershould not support a flame in the absence of an external flame.

The preferred materials for use as the foamed layer are those which are(i) fire-retardant and (ii) stable at temperatures up to about 200° F,and preferably up to about 325° F. The foam materials that meet thesecharacteristics are thermosetting materials, or if they arethermoplastic, very high temperature thermoplastics. The foam shouldalso be sufficiently flexible so that it may be bent during forming, andis preferably resistant to perspiration and washing, and even drycleaning.

The following are the preferred materials for forming the foam layer:

1. Polyolefin foams such as prepared from polyethylene, cross-linkedpolyethylene and polypropylene. Characteristics of polyethylene foamsare disclosed in the Journal of Cellular Plastics, January, 1969, atpages 46-50, which disclosure is incorporated herein by reference.Particularly preferred are fire retardant polyolefin foams, such as fireretardant polyethylene. A useful method for fire retarding polyethyleneand other polyolefins is to incorporate into the polymer fire retardantadditives such as the Diels-Alder adducts of a hexahalocyclopentadiene,such as hexachlorocyclopentadiene. Particularly useful adducts for thispurpose are disclosed in U.S. Pat. No. 3,403,036 and British Pat. No.1,305,834, the disclosures of which are incorporated herein byreference. A metallic additive such as antimony trioxide is alsodesirably incorporated in the polymer together with the disclosedadducts.

2. Polyurethane foams such as those prepared from polyether polyols orpolyester polyols and mixtures thereof. The polyether urethanes arepreferred and especially preferred as the fire retardant polyetherurethanes. The polyether urethanes can be rendered fire retardant by theincorporation of non-reactive additives, usually phosphorus-containingor halogenated compounds, but fire-retardant concentrations are held atlow levels to prevent degradation of foam properties. A typicalnon-reactive additive is a chlorinated phosphorus-containing esterproduced by Monsanto Chemical Company under the tradename Phosgard2XC-20. Reactive compounds can also be included in the polyetherurethanes to provide fire retardance. This method is disclosed in U.S.Pat. Nos. 3,278,580 and 3,391,092, the disclosures of which areincorporated herein by reference. The latter method involves utilizationof chlorendic acid as the basic component in the formation of thepolyether polyol. Another approach is a system of post-treating flexiblefoams with fire retardants. The system involves soaking the finishedfoam in aqueous suspensions of inorganic flame retardants such asmagnesium ammonium phosphate and water-soluble binders that are waterresistant after drying. After the foam has dried, the flame-retardantcharacteristic is permanent and there is no loss of foam properties.Another approach to fire retarding the polyether urethane foams involvesthe production of "high resilience" foams such as disclosed in Journalof Cellular Plastics, July/August, 1972, at pages 214-217, thedisclosure of which is incorporated herein by reference. Additionaluseful fire retardant urethane foams utilizing additives such astris(dibromopropyl) phosphate and tris(dichloropropyl) phosphate, aredisclosed in Journal of Cellular Plastics, November/December, 1970 atpages 262-266 and Journal of Cellular Plastics, May/June, 1972 at pages134-142, both of which are incorporated herein by reference. Fireretarded polyester-urethane foams are also useful such as thosedisclosed together with additional polyether urethane foams in Ind. Eng.Chem. Prod. Res. Develop., Volume 11, No. 4, 1972 at pages 383-389, thedisclosure of which is incorporated herein by reference. Additional fireretardant urethane foams are disclosed in the Journal of CellularPlastics, September/October, 1971, at pages 256-263, the disclosure ofwhich is incorporated herein by reference.

3. Fire retardant ABS foams (acrylonitrile-butadienestyrene) areprepared in fire retardant form by preparing the ABS compositions, forexample, composed of 30% acrylonitrile, 35% butadiene, and 35% styrene,as is well known in the art. The fire retardant materials and processesfor incorporating them into the ABS compositions are essentially thesame materials and processes as those described hereinbefore forincorporation into polyolefin foams.

4. Fire retardant polyester foams are also suitable. Polyester foamsgenerally are formed by reacting a polyol, generally a polyester polyolor polyether polyol with a polycarboxylic (preferably a dicarboxylic)acid such as adipic acid or sebacic acid. Typical polyols includebutanediol and polytetramethylene ether glycol. Fire retardantproperties may be incorporated into the polyester by preparing thepolyester and then soaking the finished foam in aqueous suspensions ofinorganic flame retardants as described hereinbefore in connection withthe polyurethane foams. The fire retardant properties also may be builtinto the foam by incorporating chlorendic acid as a partial or totalreplacement for the carboxylic acid, as disclosed in U.S. Pat. No.2,606,910 which is incorporated herein by reference. The polyester foamsare generally foamed by admixing a blowing agent utilizing similartechnology to that used in forming polyolefin foams.

5. Although polyvinyl chloride foams generally are not stable attemperatures above 160° F, a polyvinyl chloride composition alloyed withan acrylonitrile-butadiene-styrene terpolymer may be used inapplications wherein stability above about 200° F is not required.Post-chlorinated polyvinyl chloride foams are stable at elevatedtemperatures. These are highly stabilized thermoplastic materials andform stable foams.

6. Suitable foams may also be formed from flourocarbon elastomers whichat present are very expensive.

7. Additional foamed plastics include acrylic, cellulose acetate andepoxy foams, such as disclosed in 1974-1975 Modern Plastics Encyclopediaat page 720, the disclosure of which is incorporated herein byreference.

The foam layers are formed using the foam producing production methodswhich are well known in the foam material technology, e.g., ModernPlastics Encyclopedia, 1974-1975, Vol. 51, No. 10A, (Oct. 1974) pages125-155 the disclosure of which is incorporated herein by reference. Theprecise foam constituents and production technique varies somewhatdependent upon the specific polymer(s) which forms the basic foammaterial. Thus, the polyurethanes may be formed in the presence of smallamounts of water which react with the isocyanate to produce carbondioxide, without requiring additional foaming agents. In some instancesfoaming gases or gas-producing materials are used. Mechanical frothingmay also be used in the production of certain foams, e.g., polyurethanesand polyesters. The polymer is dispersed in water, e.g., 40-65% byweight of solids and mechanically mixed by a high shear mixer toincorporate air and is then cast on sheet material and dried by heatingto remove water.

The foam layer may be produced directly on the plastic sheet member oron a fabric layer using the direct coating process. The transfer coatingprocess also may be used in which the foam material is knife coated onrelease paper (generally silicone treated paper) and then transferred toa fabric or the plastic sheet member or even a metal substrate andcured. In the usual instance it is contemplated that the foam layer willbe formed on a fabric or a inert high temperature substrate such as apolished metal, and cured. If a fabric is used, it should be a hightemperature stable fabric, such as the high temperature stabilizedpolyesters and/or nylons. High temperature stabilized polypropylene suchas a needle punch polypropylene fabric about 8-10 mils thick is alsosuitable. Although a fabric may be used, it is not necessary in order toproduce a pleasing and even a decorative effect. These may be produceddirectly on the surface of the foam using printing or embossing rolls.

The foam layer may be fixed to the plastic sheet member by conventionalmethods such as the use of adhesives, application of pressure, flamebonding, etc. The bonding method selected depends upon the compositionof the plastic sheet member and the composition of the foam layer. Whenthe plastic sheet member is a polyvinyl chloride composition, and thefoam layer is a polyolefin foam or an ABS foam, the preferred method ofbonding utilizes ethylenevinylacetate copolymer as an adhesive to formthe bond. Polyether polyurethane foams and polyester foams are alsopreferably bonded to polyvinyl chloride sheet composition using anadhesive, preferably a thermosetting polyurethane such as a hydroxylterminated hexanediol adapate polyester cross-linked with about fourpercent of 4,4'-diphenol methane dioscyanate. The said thermosettingpolyester urethane adhesive is preferably halogenated to further theflame-retardant characteristics of the orthopedic device. The saidthermosetting polyurethane adhesive is also useful for bonding polyvinylchloride foams to polyvinyl chloride sheet material.

Polyester polyurethane foams are preferably flame bonded to polyvinylchloride sheet material.

Foam layers, preferably those having a coarse interconnected cellularstructure (at least at and near the skin) may be fixed to athermoplastic sheet member by heating the thermoplastic sheet memberuntil it has softened and contacting the sheet member and the foam layerunder pressure, e.g, by passing the heated thermoplastic sheet memberand the foam layer through rolls.

The strength and flexural properties of the orthopedic device at ambienttemperatures are largely contributed by the plastic central member. Thismember is strong and has the ability to be resilient in someconfigurations and sizes. It has the ability to be substantially rigidin specific configurations, i.e., O-sections, L-sections, U-sections,etc. A device may include several different configurations and besubstantially rigid in a specific area and quite resilient in anotherarea thereof.

The versatility of the orthopedic devices is illustrated by thefollowing properties of the plastic sheet. Different configurations wereprepared from sheet (90-93 mils thick having the composition illustratedhereinafter. The sheet was 63/8 inches long.

An "O" configuration was prepared with a radius of tube of 13/16 inches.The tube was held with clamps at each end. It was supported on two focalpoints 4 inches apart at the bottom, and the load applied from the topto the center of the tube. The deflection follows:

    ______________________________________                                        Machine Deflection.sup.(a)                                                    in Inches         Load in Pounds                                              ______________________________________                                        0.1                49.5                                                       0.2                51.2                                                       0.3                80.5                                                       0.4               104.0                                                       0.5               125.0                                                       0.6               142.0                                                       ______________________________________                                         .sup.(a) The machine deflection includes bending of the tube over its         entire length, and flattening of the tube at all three focal points.     

a. The machine deflection includes bending of the tube over its entirelength, and flattening of the tube at all three focal points.

A "U" configuration was prepared with a 23/8 inches width ofconfiguration and a 29/32 inch radius of bend. The arms of the "U" weremounted parallel to the horizontal (held in vice) and the load appliedto the upper arm. A constant load test provided the following:

    ______________________________________                                        Points at which Constant Load                                                 (1 lb.) was Applied, Measured                                                                    Deflection in Inches at                                    in Inches from Center of "U"                                                                     Constant Load (logarithm)                                  ______________________________________                                        1.15               0.050                                                      1.75               0.095                                                      2.75               0.135                                                      3.75               0.175                                                      4.75               1.145                                                      ______________________________________                                    

A constant deflection test provided the following data:

    ______________________________________                                        Points at which Constant Deflec-                                              tion (0.45 inches) was Obtained,                                                                  Load in Pounds at                                         Measured in Inches from Center                                                                    Constant Deflection                                       of "U"              (logarithm)                                               ______________________________________                                        4.75                 0.30                                                     3.75                0.60                                                      2.75                1.18                                                      1.75                8.60                                                      1.15                10.73                                                     ______________________________________                                    

Two "L" shaped configurations were prepared by holding in a vicevertically and bending to form a right angle. The load was appliedvertically and placed on horizontal arm.

The results of a constant load test on a sample having a 2 7/16 incheswidth of configuration and 1/4 inch radius follows:

    ______________________________________                                        Points at which Constant Load                                                                    Deflection in Inches                                       (2 lbs.) was Applied, Measured                                                                   at Constant Load                                           in Inches from Center of Bend                                                                    (logarithm)                                                ______________________________________                                         0.5               0.010                                                      1.0                0.025                                                      1.5                0.070                                                      2.5                0.280                                                      3.5                0.680                                                      4.5                1.150                                                      ______________________________________                                    

The results of a constant deflection test on a sample having a 23/8inches width of configuration and a 29/32 inch radius follows:

    ______________________________________                                        Points at which Constant Deflec-                                              tion (0.35 inches) was Obtained,                                                                  Load in Pounds at                                         Measured in Inches from Center                                                                    Constant Deflection                                       of Bend             (logarithm)                                               ______________________________________                                        4.5                  0.50                                                     3.5                  1.00                                                     2.5                  2.27                                                     1.5                 12.00                                                     1.0                 40.00                                                     ______________________________________                                    

The physical properties of the plastics vary somewhat with the thicknessof section tested. Specific physical properties such rigidity and/orresilience of the orthopedic support vary with the thickness and overallsize dimensions of the plastic central layer. The central plastic layeris usually between about 50 mils and about 120 mils, although thickerlayers, e.g., up to about 250 mils thick, may be utilized for largesections, such as a major body cast, e.g., about 200 mils thick, wheresubstantial rigidity is required to support a large weight. Thicksections, e.g., about 150-170 mils, would also be used to provideorthopedic devices used to precisely position the body portion forradiation therapy. Devices (in blank form, i.e., flat) used forpreparing back supports, are preferably about 65-80 mils thick. Blanksfor splints and braces are preferably about 80-120 mils thick. Thepreferred blanks for highly shaped casts may be of a variety of widthsdependent upon the final configuration and service requirements. Whenthin devices, e.g., 40-50 mils of plastic central member, are used,additional strips or pieces of plastic sheet may be fixed to the outsidesurface to reinforce the device.

The plastic preferably has a tensile strength (at yield) of between2,000 and 10,000 psi and more preferably between 5,000 and 8,000 psi(ASTM D-638). The central plastic layer is relatively stiff as reflectedby a percent elongation at yield of between about 3 and 30% andpreferably between about 4 and 8%. The properties to yield are moreimportant than to rupture since the properties should not exceed yieldin service.

The flexural strength (ASTM-790) is between 3,000 and 14,000 psi andpreferably between 8,000 and 12,000 psi. The flexural modulus (ASTM-790)is between 0.5 × 10⁵ and 7 × 10⁵ psi and preferably between 2 × 10⁵ and5 × 10⁵ psi. The notched Izod (ASTM D-256) in foot-pounds per inch isbetween 0.3 and 30 and preferably between 0.5 and 15.

The Rockwell hardness is between 15 R scale and 55 D scale andpreferably between 90 and 100 R scale. The Vicat softening point (ASTMD-1525-70) is between 60° C and 80° C.

A sample of the preferred impact modified polyvinyl chloride plasticmember which is illustrated in the Example has an average tensile (± 100psi) at yield of about 7,550 psi and at rupture of about 3,800 psi (ASTMD-638). The average (± 0.5% percent elongation at yield is 5% and theaverage percent elongation at rupture is 14.2%. The average flexuralstrength is 10.8 × 10³ psi and the flexural modulus is 4.1 × 10⁵ psi(ASTM d-790).

Another sample of the same composition had a tensile strength at yieldof 6,785 psi; an elongation at yield of 5.6%; a flexural modulus of 3.94× 10⁵ psi; a flexural strength of 11,612 psi; a Rockwell R of 94; aVicat of 74° C; and a notched Izod of 0.91 foot pounds per inch.

Another sample of the same composition which had been severely workedduring processing, but found operative had a tensile strength at yieldof 3,620 psi; an elongation at yield of 4.5%; a flexural modulus of 1.06× 10⁵ ; a flexural strength of 3,724 psi; a Rockwell R of 19; a Vicat of63° C; and a notched Izod of 12.5 foot pounds per inch.

The central plastic member may be formulated from various polymersystems; such vinyl-chloride-propylene copolymersvinyl-chloride-ethylene copolymers, or the corresponding interpolymercontaining diallyl maleate. It is preferred to utilize an impactmodified polyvinyl chloride (PVC) composition utilizing a PVC resinhaving a number average molecular weight of 20,000-23,000. Thecomposition contains between about 10 and 14 parts of an impactmodifier, between 11/4 and 2 parts of lubricant, and between 71/2 and81/2 parts of a plasticizer, per 100 parts of polyvinyl chloridehomopolymer resin. The composition will also contain stabilizers (6-9)parts and various processing aids (1.5-2.1 parts) and usually pigments(up to 5 parts).

A preferred PVC composition and exemplified composition follow:

    __________________________________________________________________________                          Preferred                                                                             Preferred                                                             Range   Composition                                     COMPONENTS            (parts) (parts)                                         __________________________________________________________________________    PVC homopolymer resin (20,000-23,000)                                                               100     100                                             impact modifier (methylmethacrylate-                                          butadiene-styrene polymer                                                                           10 - 14 12.0                                            processing aid (acrylic type)*                                                                      1.5 - 2.1                                                                             1.8                                             lubricant                                                                     blend of olefinic monoglyceride                                               and hydrogenated olein                                                                              1 -  1.5                                                                              1.25                                            tri-stearyl citrate   0.25 - 0.35                                                                           0.3                                             plasticizer (di-2-ethylhexyl phthalate)                                                             7.5 - 8.5                                                                             8.0                                             stabilizer boosters                                                           epoxidized soybean oil                                                                              4 - 6   5.0                                             mixed di- and tri-nonylphenyl phosphite                                                             1.25 - 1.75                                                                           1.5                                             polyvinyl alcohol     0.05 - 0.08                                                                           0.0675                                          stabilizers                                                                   calcium stearate      0.24 - 0.30                                                                           0.27                                            stannous stearate     0.37 - 0.43                                                                           0.40                                            zinc stearate         0.28 - 0.34                                                                           0.31                                            pigments              2.5 - 3.5                                               rutile grade TiO.sub.2        3.25                                            Hosterperm Red                0.0054                                          Indofast Orange               0.0135                                          __________________________________________________________________________     *Rohm & Haas K-120 N                                                     

A sheet of the polyvinyl chloride having a thickness of about 80-90 milswas prepared from small pellets about 1/8 inch × 3/16 inch in diameter.The pellets were heated in an extruder and the resin compositionextruded in the form of a rope-shaped material of a diameter of about1/2 inch which is then milled in rollers and calendared into sheet about15-20 mils thick. Four sections of such sheet were laminated together ina press with a heated die to form sheets about 80-90 mils thick. Thephysical properties of this test sheet were reported hereinbefore.Additional details concerning the said plastic compositions and themanner of producing them are disclosed in copending application, Ser.No. 465,403, filed Apr. 29, 1974 entitled "POLYVINYL CHLORIDECOMPOSITION" and naming AXEL W. TYBUS and LEONARD A. FABRIZIO as theinventors. The disclosure of said copending application is incorporatedherein by reference.

The polyvinyl chloride sheet material may be formed in production byheating the small PVC composition pellets in an extruder and directlyextruding in sheet form having the desired thickness. An alternateprocedure is to mill and calendar rope-shape material of a diameter fromabout 1/2 inch to 4 inches. Sheet material taken from such processes andparticularly direct extrusion is stressed and is preferably stressrelieved by annealing at temperatures of about 320° F. It is possible toanneal simultaneously with the application of an adhesive or an adhesiveand fabric.

The outside layer which is preferably fabric (but could also be anothermaterial such as a metallic layer) protects the plastic surface fromdamage during shipment, storage and handling of the flat orthopedicdevice before it is molded and also to protect it after it has beenshaped. If a heating element is used, for example, a hot iron, directlyin contact with the orthopedic device, the outside fabric layer servesto prevent adherence of the plastic to the heating element.

This outside layer also functions together with the insulating fabriclayer to maintain the coherency of the orthopedic device when it isheated to elevated temperatures. Since the outside fabric layer isbonded to the plastic, it will be in tension when the orthopedic deviceis shaped into a curve with the outer fabric layer on the outside of thecurve. It is, therefore preferably of a resiliant or stretch materialwhich will not apply pressure on and tend to distort the plastic layerat ambient and particularly at elevated shaping and/or formingtemperatures.

During heating, the outside fabric layer may be subjected to very hightemperatures. The preferred fabrics are those resistant to prolongedheating at 250° F and short term heating to substantially highertemperatures. These high temperature resistant fabrics include the hightemperature stabilized nylons; the high temperature stabilizedpolyesters; the Spandexs (polyurethanes); the aramids, such as Nomex;high temperature acrylics; the aforedescribed Collins & Aikman blends of50% Kynol and 50% Nomex and particularly the lighter weight fabrics; andlinen. The said nylons, polyesters, and aramids, are preferred.

For devices which are not to be heated to elevated temperatures, i.e.,they are available in blanks generally conforming to the desired endshape, and which are only heated for forming, lower temperature fabrics,such as cotton and wool may be used.

The outside fabric layer is at least about 4 mils thick, and preferablybetween about 4 and 22 mils thick and most preferably between about 10and 15 mils thick. It is preferably affixed to the plastic centralmember by an adhesive such as a thermoplastic polyurethane resin. Eventhinner outside layers may be used, e.g., only 1-2 mils of metal platedor laminated on the plastic sheet member. The protective layer need notcover the entire surface of the one side of the plastic sheet, e.g.,portions of the plastic may be covered by reinforcing plastic sheetstrips.

The outside fabric layer may be fixed to the central plastic layer.Orthopedic devices have been prepared by first affixing a insulatingfabric layer to the central plastic member by passing a three-layeredmaterial comprising the central plastic member and extruded polyesterfilm of about 21/2 - 3 mil thickness and the 7 oz. Collins & Aikmanfabric described hereinbefore through a Reliant roll press which was at350° F and applying 1-2 psi for 18 seconds. The extruded polyester filmwas a thermoplastic. The other fabric film, the 4 oz. Collins & Aikmanfabric described hereinbefore, was then affixed to the other side of thecentral plastic member by passing the aforedescribed insulated fabriccoated central plastic member together with said fabric and aninterposed 21/2 - 3 mil sheet of the polyester film through the Reliantroll press under the aforesaid conditions. It is preferred to producethe orthopedic device by passing the two outer layers and the centralplastic member and the respective adhesive layers, which may bepreapplied to the fabric or plastic foam, through the roll presssimultaneously to produce the integral orthopedic device in a singlepass. The blank orthopedic device may also be prepared by extruding theplastic sheet member onto a coated fabric or even coextruding the fabriclayers and the plastic sheet together with the intervening adhesives.

At the shaping and forming temperatures the orthopedic device is readilycut. The cutting may be carried out by shears, for example, a scissorsor other sharp edge. Those orthopedic devices having both sides of theplastic member covered by fabric layers retain integrity even atelevated temperatures. When it is desirable to carry out extensiveshaping and forming of the orthopedic device such as forming a coil bywrapping various layers of the orthopedic device about each other in aspiral, the temperatures may be elevated, e.g., up to about 250°-400° F.At these temperatures the device maintains its integrity but becomeshighly pliable. The orthopedic device may be cut and the plastic doesnot run out from between the outer layers. When the orthopedic device isheated to such high temperatures and removed from the source of heat, itmay be shaped and molded and formed over a period up to about 6-10minutes. The rough shaping is carried out as the orthopedic devicebegins to cool from this elevated temperature. When the outer surface ofthe insulating layer is cooled sufficiently, it may be pressed againstthe body portion to be formed into its final shape, generally underfinger pressure. After the orthopedic device is applied against thebody, there is still sufficient time during which final molding toconform to the desired body and/or device shape may be carried out.

The orthopedic device may be heated in a constant temperature fluidbath, such as a water bath or a hot oven or radiant energy. It ispreferred that heat be applied only to the side of the orthopedic devicewhich will not be applied against the patient. This may be accomplishedby radiant heat, a hot air gun or hairdryer and preferably because oftheir ready availability, a hot plate or tray and an iron in the form ofthe familiar hot tray, home iron or even a special round or curved iron.Surprisingly, it has been found that the hot surface of an iron whichmay be as hot as 300°-500° F, may be applied to the fabric layer of theorthopedic device and heat it to temperatures at which it becomesextremely pliable so that it may be cut and shaped to extremely complexshapes. The heat source is removed and/or intermittently applied and theorthopedic device applied against the body portion and molded to thedesired shape. The molding or forming may be carried out by fingerpressure. The person applying and forming the orthopedic device may weargloves. When a hot tray is used and the device covered by a protectivedome, a temperature of 200° F will over a period of time furnishsufficient heat so that the device will remain formable for the desiredworking time.

The upper temperature limit which may be applied against a portion ofthe human body varies dependent upon the area of skin in contact withthe heat, the time of contact, and the individual tolerance to hightemperature. For the purpose of applying orthopedic devices, thetemperature should not be above about 120°-125° F for short term contactand preferably below 120° F for contact of several minutes.

When the orthopedic device in blank form is pre-cut and requires onlyforming, it may be heated to a temperature between about 165°-225° Ffrom one side, and when the outside of the insulating fabric layer issufficiently cool, applied to the patient's body and formed into thedesired contoured shape.

The central plastic member of the orthopedic device exemplified herewithsolidifies at a temperature of about 129°-130° F. As a consequence, itis necessary that the temperature of the plastic central member shouldbe above about 130° F during forming. Since application of thistemperature to the patient's skin for more than a very short time isuncomfortable and possibly dangerous, the outer temperature of theinsulating fabric layer should be at least 25° F cooler than thetemperature of the plastic central member during forming, and ispreferably at least 30° F cooler. It is even more preferred that theouter temperature be at least 35° F or 40° F cooler than the plastic.The foregoing particularly applies during the plastic forming range of130° F up to about 160° F. The temperature at which the plastic sheetmembers softens permitting the orthopedic device to be formed may bevaried from about 120°-123° F, up to about 145°-155° F by varying thecomposition of the polyvinyl composition comprising the central plasticsheet. The aforenoted temperature difference may be larger, e.g., atleast 50° or 60° F when the device softens at a higher minimumtemperature, e.g., above about 145°-155° F. A foam insulating layer isparticularly suitable.

In a preferred embodiment of the invention, the heat is applied againstthe side of the orthopedic device covered by the outside fabric layer.For some service conditions it is contemplated that both sides of theplastic central member may be covered by insulating material. This wouldpermit the entire member to be heated to an elevated temperature andretain the heat for a longer period of time.

The molded orthopedic device may be in many forms dependent upon theintended service and particularly the portion of the body to which it isapplied. The orthopedic device when manufactured will be in the form ofsheet material. For most purposes, these sheet blanks will be in avariety of sizes such as squares from about 4 inches on a side up toabout 2 feet on a side and even larger sizes, eg: 2 × 4 feet or more.Rectangular and even oval or round blanks may be prepared. These blankswill have the central plastic member in sheet form with the insulatinglayer bonded on one side and the other layer bonded on the other side.Such blanks may have a total overall thickness somewhat less than thesum of the thickness of the plastic central member plus the two outerlayers as a result of the manufacturing process which involves theapplication of pressure either in the form of a press or more usually inthe form of pressure rolls.

The invention is further illustrated by the following Example anddrawings:

FIG. 1 of the drawing illustrates a rectangularshaped blank (flatorthopedic device) 10 having a protective fabric layer 13 on one side ofthe plastic sheet 12 and the insulating layer 11, 20 on the other side.

FIGS. 2a and 2b illustrate two embodiments of the invention along line2--2 of FIG. 1.

FIG. 2a illustrates a preferred embodiment of the invention in which theinsulating layer 11 is on one side of the plastic sheet 12 and the otherside of the plastic sheet 12 is covered by the protective fabric layer13. The relative thickness of the layers in all the drawings is forillustrative purposes only.

FIG. 2b depicts a preferred embodiment of the invention in which oneside of the plastic sheet 12 is covered by the protective layer 13 andthe other side is covered by the insulating layer 20.

FIG. 3 illustrates a shaped and formed back support 14 with formedcontours such as those illustrated at 15 and 15'. The central portion 19is relatively fixed and supports the spinal area and portions 15 and 15'are more resilient and support the back and related lower body portions.

FIG. 4 illustrates an arm splint 16 having hand section 17, wristsection 18, and forearm section 19, with the insulating foam layer 20(not depicted in the edges) on the inside surface and a protective layer13 on the outside surface.

The invention is further illustrated in the following Examples. Allparts and percentages are by weight unless specified otherwise.

EXAMPLE 1

A flat blank orthopedic device was formed from a plastic sheet member ofa thickness of 91-93 mils and having the composition set forth in therighthand column of the table hereinbefore was coated on one side withthe woven insulating fabric which is the non-burning blend of 50% Kynoland 50% Nomex described hereinbefore. This insulating fabric had aweight of about 7 ounces per square yard and was about 14 mils thick. Itwas impregnated from one side with a polyester flexible polyurethanethermoplastic adhesive to a depth of about 3 mils on one side. A thincoating remained on the side to which the impregnant was applied. It wasbonded to the plastic member by heating the impregnated insulatingfabric to a temperature of about 325° F and then covering the plasticsheet and applying light pressure. The other side of the plastic sheetwas covered by a knit stabilized nylon fabric of a thickness of about 14mils similarly impregnated with the same adhesive. It was similarlybonded to the plastic member.

EXAMPLE 2

One-hundred parts of a fine powder, e.g., 40-50 microns, of a partiallycross-linked polyethylene which will produce a generally stiff butflexible foam is mixed with 6-10 parts of titanium dioxide pigment andabout four parts of bisazodicarbonamide, and mixed until homogenous. Itthen was spread in a thin sheet on silicone coated paper and passed intoan oven and heated to 170°-190° C over a period of up to about tenminutes. The bisazodicarbonamide decomposes liberating nitrogen andcausing formation of foam. The resultant foam layer is about 125 mils.Another thicker layer was formed to about 250 mils. The newly formedfoam is then cooled quickly by passage through a cold water trough. Theresultant foam was sufficiently flexible to be bent back up on itself.Its density is 4.1 pounds per cubic foot. The pores are predominantly ofthe closed type in the area of the skin.

Samples of sheet of the above foam about 125 mils thick, and also of 250mils thick, are adhered to a sheet of said central plastic member formedfrom PVC with the thermosetting polyurethane adhesive desiredhereinbefore. The other side of the PVC was coated with the tricot asdescribed in Example 1. The resultant device had desirable orthopedicdevice characteristics. The disadvantage was that the polyethylene wasnot fire retardant.

EXAMPLE 3

Example 2 is repeated using a fire retardant composition comprising 75parts of polyethylene, 25 parts of the Diels-Adler diadduct ofhexachlorocyclopentadiene and 1,5-cyclooctadiene, 10 parts of antimonytrioxide, 6-10 parts of titanium dioxide, and about 4 parts ofbisazodicarbonamide. A third foam layer about 50 mils thick is used inplace of the thicker layers of insulating foam in Example 2.

EXAMPLE 4

Example 2 is repeated substituting for the polyethylene foam of Example1, a polyethylene foam having a density of 4.0 pounds per cubic foot, athermal conductivity of 0.40 Btu/Sq. ft./hr. degrees F/inch as measuredby ASTM D2326, a water vapor transmission as measured by ASTM C355 of <0.40 perm-inch and a water absorption of < p. 50 percent by volume (96hours) as measured by ASTM D2842.

EXAMPLE 5

Example 2 is repeated using a cross-linked polyethylene foam having adensity of about 4 pounds per cubic foot, a thermal conductivity of 0.40Btu/sq. ft./hr. degrees F/inch as measured by ASTM D2326, a water vaportransmission of <0.40 perm-inch as measured by ASTM C355 and a water aabsorption of <0.50 percent by volume (96 hours) as measured by ASTMD2842.

EXAMPLE 6

Example 2 is repeated using a commercially available fire retardantpolyurethane foam having an ASTM D1692-68 classification of SE(self-extinguishing) and a density of 4.18 pounds per cubic foot (67kg/m³). A foam layer about 25 mils thick is used in place of the thickerfoam layer of Example 2.

EXAMPLE 7

Example 2 is repeated using a fire retardant composition comprising 60parts by weight of polypropylene, 27 parts by weight of the Diels-Adlerdiadduct of hexachlorocyclopentadiene, 1,5-cyclooctadiene, 13 parts byweight of antimony trioxide, 6-10 parts of titanium dioxide and about 4parts of disazodiacarbonamide.

EXAMPLE 8

Example 2 is repeated using a flexible polyurethane, foam having adensity of two pounds per cubic foot and a thermal conductivity of 0.3Btu/sq. ft./hr. degrees F/inch as measured by ASTM D2326.

EXAMPLE 9

Example 2 is repeated using a high resilience polyurethane foam having adensity of 2.7 pounds per cubic foot and a flame resistancecharacteristic of SE (self-extinguishing) as measured by ASTM D1692.

EXAMPLE 10

Example 2 is repeated using a flexible polyurethane foam as prepared inExample 4 of U.S. Pat. No. 3,391,092, the disclosure of which isincorporated herein by reference.

The thermocooling characteristics of the various components of theorthopedic device when heated to high temperatures, for example, about300° F are illustrated in the following time-temperature profile of aflat (blank) about 61/2 inches × 61/2 inches. The central plastic memberwas about 69 mils thick. The insulating fabric was the aforedescribedCollins & Aikman no-burn fabric (7 oz. weight) about 15-18 mils thick.The other fabric was a knit (tricot) stabilized nylon and polyesterblend about 12 mils thick. Both of the fabrics were applied to theplastic member by spreading an adhesive on one side of the plasticmember and then applying the fabric and applying a heated iron to heatthe fabric and adhesive to the temperature range to about 350°-380° F.The adhesive was spread to a thickness of about 3 mils. The insulatingfabric was applied using the thermoplastic polyurethane adhesivedescribed hereinbefore. The tricot adhesive was the thermosettingpolyurethane described hereinbefore containing about 4% of thecross-linking diisocyanate.

The thermal properties were determined by first heating the device andthen allowing it to cool in air (room temperature 69°-71° F) andmeasuring the rates thereof. The device was positioned with the tricotfabric face about 3/8 of an inch away from the hot plate and parallelthereto. The hot plate was measured to have a surface temperature ofabout 409° F. The device was heated to the temperatures noted in thefollowing table and then permitted to cool. A thermocouple T₃ waspositioned on the central plastic member face which is bonded to thetricot and a thermocouple T₄ was on the side of the plastic member whichis bonded to the insulating fabric. The time-temperature profilefollows:

    ______________________________________                                                     Time      Temperature ° F                                              (minutes) T.sub.4  T.sub.3                                       ______________________________________                                        Heating        0            82       82                                                      10          192      209                                                      17          224      234                                       Heat Source Removed                                                                          21.5        268      323                                       Cooling        0.5         263      284                                                      1.0         252      267                                                      1.5         242      251                                                      2.0         227      237                                                      2.5         219      225                                                      3.0         206      213                                                      3.5         195      201                                                      4.0         186      192                                                      4.5         177      182                                                      5.0         168      173                                                      5.5         161      166                                                      5.8         157      161                                                      8.0         131      134                                                      10.0        115      118                                                      11.5        106      108                                       ______________________________________                                    

Physical manipulation of the device established that the forming periodended, i.e., the plastic had solidified, when the plastic temperaturewas about 130° F. In some cases this appeared closer to 129° F which iswithin the range of accuracy of measurement. The same device wasreheated several times and each time it solidifies at about 130° F.Other samples softened at somewhat lower temperatures, e.g., 124° F-127°F.

This data is consistent with the developmental experience that the samedevice may be completely or partially reformed. and even reshaped, inwhole or in part, many times. This provides means for correcting"fitting" errors, and also means for adjusting the shape of the deviceduring its service life. It also provides the possiblity of reusing thedevice which is particularly important in the poorer countries.Orthopedic devices having the insulated foam layer in place of thefabric layer provide even more forming time with at least as muchprotection to the patient.

The aforesaid time-temperature profile establishes that there was morethan eight minutes of shaping and forming time, i.e., the time startingwith the removal of the heat source, until solidification occurs.Practical testing of numerous samples having the nylon-polyester fabricon one side and the no-burn Collins & Aikman insulating fabric on theother side has established that when the device has been heated to over300° F and preferably to 325° F, there is at least 71/2 minutes ofshaping and forming time. Tests with other experimental devices in whichthe other fabric is not nylon-polyester, for example, cotton, haveestablished that the cooling time to solidification may be different andin some cases appreciably shorter, for example, as little as 41/2minutes.

The actual cooling time for a given device may vary with the overallthickness and other dimensions of the device as well as the amount ofheating time and ultimate temperature and and the cooling conditions.The devices having the insulating plastic foam layer, particularly thicklayers, e.g., 125-250 mils thick, cooled more slowly and provided alarger temperature differential, e.g., at least 55°-60° F, between theoutside of the foam layer, and the plastic sheet member.

Temperature determinations were also made on the outside of theinsulated fabric layer during the timetemperature profile, and duringother heating and cooling tests. It was found that when using theaforesaid 7 oz. Collins & Aikman no-burn fabric, the temperaturedifferential between the outside of the fabric and the plastic was about40° F. The temperature measurements sometimes indicated a variation of ±10° F, but were usually within ±5° F.

When the "blank" orthopedic device is severly shaped at temperaturesabove about 325° F, e.g., some portions bent around one axis and otherportions bent around a perpendicular or other intersecting axis, theremay be some displacement of plastic within the outer layers so that theresultant shaped (and usually formed) device may no longer be of aconsistent uniform thickness.

Some practitioners who apply the orthopedic devices may wish to outlinethe shape, particularly when the shape is relatively intricate, in apattern on the blank (flat) orthopedic device before cutting it into therough shape and forming. This may be accomplished in several methodsdepending upon the fabrics involved. Certain fabrics, e.g., the wovenblend of Kynol and Nomex described hereinbefore, may be marked with amarker, e.g., pen, pencil, crayon, etc. Alternately, a paper layer maybe affixed to one of the surface layers by a pressure-sensitiveadhesive. The surface of the paper may be marked and used as a patternand the orthopedic device cut and shaped. The paper may be removedimmediately after cutting or in some cases desirably retained untilrough shaping is completed. It would then be stripped from the outerlayer.

The orthopedic devices of the present invention have many advantages.When used as a relatively large support without severe bending, such asa back support, the orthopedic device supplies resilient support. Whenused as a cast it will immobilize. When used to keep a body part in bentposition such as a knee cage, restraint in only one direction isrequired. The orthopedic devices have special utility for service whereadjustment in the shape of the device is desirable during a protractedperiod of time. Thus, as the patient responds to treatment, change inposition may be desirable. In the past with plaster casts, the old casthad to be removed and a new cast formed. The orthopedic devices of thepresent invention may be partially reshaped even when attached to thebody by localized application of heat and molding.

One of the most important uses of orthopedic devices is support of thelumbo-sacral region of the back. Immobilization of the lower body arearisks a number of ill effects including shrinkage of tendons, andelasticity loss and weakening of muscles. The orthopedic devices of thepresent invention provide effective support and permit stabilization andimmobilization of the lower spine without the foregoing adverse effects.This results from the unique combination of physical properties whichprovide substantial immobilization by those portions of the device whichare highly contoured and at the same time provide resilient support byother less contoured portions of the back support and thereby permitbody movement. Because of the ability to be formed and molded directlyupon the patient, it is possible to provide back supports (which havebeen impossible or very difficult to make using prior materials) whichcover relatively diverse and/or large portions of the back and, in somecases, may overlap around the sides of the body or over the shoulder.

The orthopedic devices may be used in the veterinary field in a mannerparallel to their use with humans.

The orthopedic devices may be placed in a pocket or pouch of a garmentwhich encircles a part of the body and thereby positions the orthopedicdevice. For many applications it will be desirable that the orthopedicdevice should be placed directly against the body portion and encircleit, and therefore it is self attaching. For other applications, theorthopedic device should have loops or other means of attachment forbelts and other types of bindings such as Velcro fasteners, etc. Thesemay be affixed to or even incorporated into one or both of the fabriclayers. In such instances they will be affixed to the fabric layer whichis on the side of the orthopedic device away from the patient's skin,i.e., in most instances the outside fabric layer. Orthopedic devices maybe formed in self-closing and fastening configurations or may befastened in any and all ways known in the art today.

The orthopedic devices may be provided as flat blanks for molding andshaping by the ultimate user. They may also be provided in preformedshapes, such as a series of preformed back supports which will generallyconform to the body portions of the appropriate size. These orthopedicdevices would have the advantage over other preformed devices in thatfinal adjustment to individual variations may be made. They will alsohave the advantages over prior orthopedic devices in their combinationof rigidity and resilience in different directions.

The orthopedic devices are also useful when utilized to position thebody (or a portion thereof) very accurately for radiation treatment.

The orthopedic devices having a foam outer surface may be used as perse, or as part of another orthopedic device to cushion or otherwiseprotect a portion (usually a boney portion) of the body).

Although the orthopedic devices will generally be conformed to the shapeof the body, they may sometimes be shaped differently so as to make thebody conform to the shape of the orthopedic device during service, e.g.,a correctly formed arch support for use by a person having a fallenarch.

The discussion hereinbefore is primarily in connection with orthopedicdevices which will be attached to the body. They may also be used inequipment which is not attached to the body but comes into contact withthe body such as the seat of a chair, particularly an orthopedic chair,foot supports such as arch supports, and other portions of shoes andboots. They may be used in ski boots wherein relative rigidity incertain directions is desired in combination with resiliance in otherdirections of movement.

What is claimed is:
 1. An integral formable orthopedic device comprisinga plastic sheet member and integral therewith an insulating layer on oneside of said plastic sheet member; and a protective layer on the otherside;said plastic sheet member being at least about 40 mils thick, andhaving a tensile strength at yield of at least about 20,000 psi, aflexural strength of between 3,000 and 14,000 psi, a flexural modulus ofbetween about 0.5 × 10⁵ and 7 × 10⁵ psi, a Vicat softening point ofbetween 60° C. and 80° C., and a Rockwell hardness of between 15 on theR scale and 55 on the D scale; said insulating layer being at leastabout 10 mils thick and having a coefficient of heat transfer belowabout 2 cal/sec/cm² /cm/°C×10.sup.⁻⁴ .
 2. The orthopedic device of claim1, wherein said insulating layer is a plastic foam layer; and whereinsaid plastic sheet member is between 50 and 120 mils thick and has thetensile strength at yield of between 2,000 and 10,000 psi, an elongationat yield of between about 3 and 30%; a flexural strength of betweenabout 3,000 and 14,000 psi, a flexural modulus of between about 0.5 ×10⁵ and 7 × 10⁵ psi, and a notched Izod of between 0.3 and 30 footpounds per inch,
 3. The orthopedic device of claim 2, wherein saidinsulating layer has a coefficient of heat transfer of below about 1.6cal/sec/cm² /cm/°C×10⁻ ⁴ and said plastic foam comprises afire-retardant plastic.
 4. The orthopedic device of claim 3, whereinwhen said device is heated by application of heat to said protectivelayer, and sufficient heat is applied so that said plastic sheet memberis heated to temperatures of above about 160° F., the insulating foamlayer has insulating characteristics such that the temperature of theoutside surface of said insulating foam layer is at least about 55° F.below the temperature of said plastic sheet member.
 5. The orthopedicdevice of claim 1, wherein when said device is heated by application ofheat to said protective layer and sufficient heat is applied so thatsaid plastic sheet member is heated to temperatures of above about 160°F., the insulating layer has insulating characteristics such that thetemperature of the outside surface of said insulating layer is at least25° F. below the temperature of said plastic sheet member.
 6. Theorthopedic device of claim 1, wherein said insulating foam layer isbetween 10 mils and 250 mils thick and is a fire-retardant plastic foamlayer.
 7. The orthopedic device of claim 4, wherein said insulating foamlayer is between 10 mils and 250 mils thick.
 8. The orthopedic device ofclaim 7, wherein said insulating foam layer is a foamed plastic selectedfrom the group consisting of polyethylenes, polyurethanes, polyesters,and acrylonitrile-butadiene-styrene.
 9. The orthopedic device of claim1, wherein said plastic sheet member is a polyvinyl chloride compositionwhich solidifies at a temperature between 120° F and 155° F.
 10. Anintegral orthopedic device comprising a central plastic sheet memberhaving one side covered with an insulating layer and the other sidecovered with a fabric layer, both of said layers being bonded to saidplastic sheet member;said plastic sheet member being between 50 and 120mils thick, and having a tensile strength at yield of above about 2,000psi, and an elongation at yield of between 3% and 30%, a flexuralstrength of between 3,000 and 14,000 psi, a flexural modulus of betweenabout 0.5 × 10⁵ and 7 × 10⁵ psi, and a Rockwell hardness of between 15on the R scale and 55 on the D scale; said insulating layer beingbetween about 10 and 250 mils thick; said other fabric layer being about4 and 22 mils thick and functioning to protect said plastic layer; andsaid orthopedic device being formable at temperatures above about 120°F.
 11. The orthopedic device of claim 10, wherein said insulating layeris a plastic foam layer, wherein said plastic sheet member has a tensilestrength at yield of between 2,000 and 10,000 psi, a notched Izod ofbetween 0.3 and 30 foot pounds per inch, and a Vicat softening point ofbetween 60° C. and 80° C.; and said insulating foam layer has acoefficient of heat transfer below about 2 cal/sec/cm² /cm/°C×10⁻ ⁴. 12.The orthopedic device of claim 11, wherein said plastic foam is selectedfrom the group consisting of fire-retardant polyolefins, polyurethanes,polyesters, and acrylonitrile-butadiene-styrene.
 13. The orthopedicdevice of claim 12, wherein said plastic sheet member has the tensilestrength at yield of between 5,000 and 8,000 psi, an elongation at yieldof between about 4 and 8%, a flexural strength of between about 8,000and 12,000 psi, a flexural modulus of between about 2 × 10⁵ and 5 ×10.sup. 5 psi, a notched Izod of between 0.5 and 15 foot pounds perinch, and a Rockwell of between 90 and 100 R; andwherein said insulatingfabric layer has a coefficient of heat transfer below about 1.6cal/sec/cm² /cm/°C×10⁻ ⁴.
 14. The orthopedic device of claim 13, whereinsaid protective fabric layer is a fabric selected from the groupconsisting of high temperature stabilized nylons, high temperaturestabilized polyesters, and aramids.
 15. The orthopedic device of claim14, wherein said plastic foam is polyethylene.
 16. The orthopedic deviceof claim 14, wherein said plastic foam is polyester polyurethane. 17.The orthopedic device of claim 14, wherein said plastic foam ispolyether polyurethane.
 18. The orthopedic device of claim 14, whereinsaid plastic foam is polyester.
 19. The orthopedic device of claim 14,wherein said plastic foam is between about 125 and 250 mils thick. 20.An orthopedic device comprising a central plastic sheet member havingone side covered with an insulating plastic foam layer and the otherside covered with a high temperature fabric selected from the groupconsisting of stabilized nylon stabilized polyester and blends thereof,said fabric layers being bonded to said plastic sheet member;saidplastic sheet member being between 50 and 120 mils thick, and having atensile strength at yield of between about 2,000 and 10,000 psi, and anelongation at yield of between 3 and 30%, a flexural strength of between3,000 and 14,000/psi, a flexural modulus of between about 0.5 × 10⁵ and7 × 10⁵ psi, and a Rockwell hardness of between 15 on the R scale and 55on the D scale; said insulating foam layer being at least about 10 milsthick; said fabric layer being at least about 4 mils thick andfunctioning to protect said plastic sheet member; and when said deviceis heated by the application of heat to the fabric side and said plasticsheet member is heated to temperatures above about 300° F., saidorthopedic device has thermal characteristics such that it may be shapedand molded for a period of at least about 41/2 minutes before itsolidifies.
 21. The orthopedic device of claim 20, wherein said plasticfoam is selected from the group consisting of fire-retardantpolyolefins, polyurethanes, polyesters, andacrylonitrile-butadiene-styrene.
 22. The orthopedic device of claim 21,wherein when said insulating foam layer is a heated by application ofheat to the fabric side, the insulating layer has insulatingcharacteristics such that the temperature of the outside surface of saidinsulating foam layer is at least about 45° F. below the temperature ofsaid plastic sheet member.
 23. An orthopedic device formable at elevatedtemperatures comprising a central plastic sheet member having one sidecovered with an insulating plastic foam layer and the other side coveredwith a fabric which will not tend to distort the plastic sheet memberwhen said device is formed, said layers being bonded to said plasticsheet member;said plastic sheet member being at least 50 mils thick, andhaving a tensile strength at yield of above about 2,000 psi, a flexuralstrength of between 3,000 and 14,000 psi, a flexural modulus of betweenabout 0.5 × 10⁵ and 7 × 10⁵ psi, and a Rockwell hardness of between 15on the R scale and 55 on the D scale; said insulating layer being atleast about 10 mils thick; and said fabric being at least about 4 milsthick and functioning to protect said plastic sheet member.
 24. Theorthopedic device of claim 23, wherein said insulating layer is a foamselected from the group consisting of fire-retardant polyolefins,polyurethanes, polyesters, and acrylonitrile-butadiene-styrene.
 25. Theorthopedic device of claim 24, wherein said plastic sheet member has atensile strength at yield of between 2,000 and 10,000 psi, an elongationat yield of between about 3 and 30%, and a notched Izod of between 0.3and 30 foot pounds per inch.
 26. The orthopedic device of claim 25,wherein said plastic sheet member has the tensile strength at yield ofbetween 5,000 and 8,000 psi, an elongation at yield of between about 4and 8%, a flexural strength of between about 8,000 and 12,000 psi, aflexural modulus of between about 2 × 10⁵ and 5 × 10⁵ psi, a notchedIzod of between 0.5 and 15 foot pounds per inch, and a Rockwell ofbetween 90 and 100 R; andwherein said insulating layer has a coefficientof heat transfer below about 2 cal/sec/cm² /cm/°C×10⁻ ⁴.
 27. Theorthopedic device of claim 21, wherein said fabric is a fabriccomprising fibers selected from the group consisting of high temperaturestabilized nylon fibers and high temperature stabilized polyesterfibers.
 28. The orthopedic device of claim 27, wherein said plasticsheet member is a thermoplastic.
 29. The orthopedic device of claim 27,wherein the plastic sheet member is a polyvinyl chloride compositionwhich solidifies at a temperature between about 120° F. and 155° F., andwherein said plastic foam is polyethylene.
 30. The orthopedic device ofclaim 27, wherein the plastic sheet member is a polyvinyl chloridecomposition which solidifies at a temperature between about 120° F. and155° F., and wherein said plastic foam is polyester polyurethane. 31.The orthopedic device of claim 27, wherein the plastic sheet member is apolyvinyl chloride composition which solidifies at a temperature betweenabout 120° F. and 155° F., and wherein said plastic foam is polyetherpolyurethane.
 32. The orthopedic device of claim 27, wherein the plasticsheet member is a polyvinyl chloride composition which solidifies at atemperature between about 120° F. and 155° F., and wherein said plasticfoam is polyester.
 33. The orthopedic device of claim 27, wherein theplastic sheet member is a polyvinyl chloride composition whichsolidifies at a temperature between about 120° F. and 155° F., andwherein said plastic foam is acrylonitrile-butadiene-styrene.